Thrust device

Abstract

A thrust device, in particular for a roller cam mechanism in a steering system, includes a first mechanism member which is held on a frame in engagement with a second mechanism member. The thrust device comprises a pressure piece which is mounted on the frame so as to be displaceable along an axis and is acted on by a spring element for pressing the first and second mechanism members against one another. In order to construct the thrust device for compensating for wear and thermal expansion of the engagement of the mechanism members and to configure it to be inexpensive and quiet during operation, there is provision for the spring element to be formed from rolling bodies which are spring loaded approximately transversely with respect to the axis of the pressure piece, the rolling bodies being supported on oblique surfaces between the pressure piece and a frame part which is configured as a setting screw or cover. The pressure piece can additionally be spring loaded axially by a compression spring.

1 . A thrust device for a roller cam mechanism in a steering system, having a frame on which a first mechanism member is arranged in engagement with a second mechanism member, and having a pressure piece which is mounted on the frame so as to be displaceable along an axis, a spring element for pressing the first mechanism member and the second mechanism member against one another acting on the pressure piece, the spring element being supported on oblique surfaces between the pressure piece and a frame part, the spring element being formed from rolling bodies which are spring loaded approximately transversely with respect to the axis of the pressure piece and the oblique surfaces are configured with an angle which opens radially toward the axis of the pressure piece, and the rolling bodies are spring loaded by a spring radially in the direction away from the axis of the pressure piece.  
   
   
       2 . The thrust device, as claimed in  claim 1  wherein, the pressure piece is spring loaded by a compression spring in the direction of the axis.  
   
   
       3 . (Canceled)  
   
   
       4 . The thrust device as claimed in  claim 1  wherein, the spring extends in each case between the two rolling bodies.  
   
   
       5 . (Canceled)  
   
   
       6 . The thrust device as claimed in  claim 1  wherein, the oblique surfaces merge with an arcuate segment having a radius into a surface which extends approximately perpendicularly with respect to the axis of the pressure piece.  
   
   
       7 . The thrust device as claimed in  claim 6 , wherein, the radius of the arcuate segment is larger than the radius of the rolling bodies.  
   
   
       8 . The thrust device as claimed in  claim 1  wherein, the oblique surfaces are arranged in the pressure piece.  
   
   
       9 . The thrust device as claimed in  claim 1  wherein, the oblique surfaces are arranged in the frame part.  
   
   
       10 . The thrust device as claimed in  claim 1  wherein, as viewed in the axial direction of the axis of the pressure piece, a flat surface or, as viewed transversely with respect to the axis, a cylindrical surface lies opposite the oblique surfaces.  
   
   
       11 . The thrust device as claimed in  claim 1  wherein, the rolling bodies are balls.  
   
   
       12 . The thrust device as claimed in  claim 1  wherein, the compression spring has a greater spring force than the spring which loads the rolling bodies.  
   
   
       13 . The thrust device as claimed in  claim 1  wherein, the spring force of the compression spring is less than 20 N.  
   
   
       14 . The thrust device as claimed in  claim 1  wherein, the frame part is a setting screw.  
   
   
       15 . The thrust device as claimed in  claim 1  wherein, the frame part is a cover which is positioned fixedly, preferably calked, in the frame.  
   
   
       16 . The thrust device as claimed in  claim 1  wherein, the pressure piece is penetrated by a hole in the axial direction.  
   
   
       17 . The thrust device as claimed in  claim 1  wherein, the frame is a mechanism casing.  
   
   
       18 . The thrust device as claimed in  claim 1  wherein, the first mechanism member is a worm and the second mechanism member is a worm gear.  
   
   
       19 . The thrust device as claimed in  claim 1  wherein, the pressure piece acts on a bearing of the first and/or second mechanism member.  
   
   
       20 . The thrust device as claimed in claims  1  wherein, the pressure piece, the spring element, the compression spring and the frame part are combined in a casing as a pressure piece assembly.  
   
   
       21 . The thrust device as claimed in  claim 1  wherein, the first mechanism member is a pinion and the second mechanism member is a rack.